Ambulatory repeating system



April 19, 1927.

R. w. MORRIS AMBULATORY REPEATING SYSTEM Filed Aug' 25, 1923 3 Sheets-Sheet 1 Ail 19 1927. Apr R. w. MORRIS nANIBULAIORY REPEATING SYSTEM sa S.

INVENTOR W /w A TTORNEY tmx 3 Sheets-Sheet 2 u. a S, u

Filed Auil- 2.5, 1925 lfi Patented Apr. 19, 1927.

narran stares Parent ortica.

ROBERT W. MORRIS, OF ROSLYN, NEW YORK, ASSGNOR TO AMERICAN TELPHONE & TELEGRAPI- COMPANY, A COREORATION OF NEW YORK.

AMBULATORY REPEATING SYSTEM.

Application lcd August 25, 1923. Serial No. 659,290.

rlhis invention relates to radio repeating systems and more particularly to radio repeating systems employing stations having an ambulatory or mobile character as distinguished from fixed repeating stations.

ln order to bridge across long distances in radio transmission it is necessary either to use high power radio transmitting apparatus or to adopt some system employing intermediate radio repeating systems. Such repeating stations in the past have been arranged at fixed points. Consequently, if it were desired to apply the repeating method to trans-oceanic communication difficulty would be encountered in establishing and maintaining suitable iiXed repeating stations of the type ordinarily contemplated. it would be necessary to make use of small and inaccessible islands for this purpose and in some cases the method might fail altogether due to the absence of such islands along the route desired.

The purpose of this invention is to employ as repeating stations radio equipment installed upon vessels traveling across the ocean over which it is desired to transmit. its is well known, vessels of this character adhere very closely in their movements to fixed schedules and it would therefore be possible at all times to keep a desired number of repeating stations at fairly uniform distances apart between any two terminal stations by mounting the repeating apparatus upon certain vessels following a given schedule. vln certain instances, the v ssels traveling in one direction may be utilized as repeaters for transmission in one direction while those vessels which are returning` may be utilized as repeaters for transmission in the opposite direction. In accorfflance with other embodiments of the invention, the repeating apparatus with which a ship is equipped may be of a twoway character so that the vessel will constitute a station for transn'iitting in either of two directions. regardless of its character. The invention also contemplates arranging the rep ating apparatus so that the original currents to be amplified will be detected during the process of amplification, thereby enabling the .receiving portion of the repeater equipment to be used for the purposeof receiving signals in the usual manner. Likewise, the sending equipment of the repeuter may be used for transmitting.

Obviously,v a syste-1n of the type above de* scribed can be used on land under certain conditions, the ambulatory stations being located on railwayv trains or other mobile vehicles.

The invention may now be more fully understood from the following detailed description when read in connection with the accompanying drawing, Figures l to 6 inclusive of which illustrate a number of diftion may be practiced.

Referring to Fig. l, two land stations X and Y are shown Working through two repeating stations designated ship station No. l and ship station No. 2 respectively, these stations being located on ships in the region between the land stations. The number of repeating stations may, of course, be in creased as required. Communication in one direction is carried on by using wave lengths al, al.; and a5 successively7 while in the reverse direction wave lengths A2, a4 and )t6 are so used.

The land station X comprises a land line L1, this land line being either a telephone or telegraph line, a transmitting channel including a modulator M1 and an amplifier TA1 connects the line L1 to a transmitting antenna AT1. The modulator may be Supplied with a carrier frequency )t1 from any suitable source such as a vacuum tube oscillator O1. it will be understood that the antenna and transmitting circuits may be tuned in accordance with the common practice in the art and that the modulator,

ferent typical methods by which the inven-` vamplifier and oscillator may be of any well known type. A receiving channel including a detecting and amplifying apparatus D1 connects the land line Ll to the receiving antenna AE1. The detecting and amplifying apparatus may be of any type well known in theart and it will be understood that the receiving antenna and other receiving` circuits may bc timed to the receiving frequency in any well. known manner. ln order that the transmitting and receiving channels may be rendered conjugate the land line L is balanced by a. suitable netword N1.

Ship station l involves a receiving antenna ARQ and a transmitting antenna All2 interconnected by two separate repeating channels. The one channel including detecting and amplifying apparatus DEZ associated with the antenna ABZ, a modulator MEZ and an amplifier EA2, the modulator being supplied with the carrier frequency as from an oscillator E02. The other channel includes the detectinO and amplifying apparatus Dld/Y2, modulator MV2 and amplifier llUrz the modulator being supplied with thecarrier frequency a2 from the oscillator NOT It will be understood that the. antenna AR: is merely conventionally indicatel7 the antenna as actually constructed being arranged so that it is resonant at either of tvo frequencies al or a4 in a manner we-ll understood in the art. Likewise, the detecting and amplifying apparatus of the two channels may be rendered selective by timing or other means well known in` the art at frequencies al and )q respectively. So., also, the transmitting portions; of the channels may be rendered selective by tuning or other well known means and the transmitting antenna AT2 may be resonant at either of two frequencies ag and A2.

The apparatus at ship station No. Q will be in all respects identical with that at ship station No. l except tor the different frequencies involved and, similarly, the apparatus at land station Y will he identical in construction with that at land station X except for the dilllerent frequencies employed. At station Y the frequency as is used for transmission and the frequency a5 for reception. All of the elements conventionally indicated at all of the stations in.

Fig. l and also in the other ligures may be of any type well known in the art except as otherwise indicated.

The operation is as follows: Telephonie or other signals incoming from land line L.,- are impressed upon the modulator M1 and modulate the carrier frequency al, the modulated carrier frequency being an'ipliticd by the amplifier TAl and radiated by the antenna AT1. The modulated carrier frcquency al is received at ship station No. l by the antenna Alti, iuqciressed upon the detector DEZ and the signal detected therefrom. The detectedsignal may he heard in the local receiver in a manner well understood in the art but for purposes of repeaing some of the detected energy is impressed upon the modulator EO.2 to ino lulate a carrier frequency as, the modulated carrier being amplified by the amplifier EAU and` radiated from the antenna ATS. At, shipstation No. 2 the modulated. carrier fre quency is received by the receiving antenna.j detected. and the detected sigiial is used to modulate the carrier frequenrv am which in turn is. radiated to the land station Y, whe-re is isv detected and in'ipressed upon the. outgoingvv land line L4.

Tn a similar' manner.y signaling' currents received from the line. LV1 modulate a carrier frequency it). at statica Y, are radiated to ship station No. '2, where they are detected in the other channel by detector DVQ, the detected oscillations modulating a carrier frequency a4, which is then amplilied and radiated from the antenna AT3 to ship station No. l. The modulated carrier ad is detected at ship stat-ion No. l by the detector Dill. the detected signaling current beinel used to modulate a carrier frequency a: which in turn is radiated to the receiving antenna llt1 at station X. The detector l/l of the receiving channel detects the signal from the frequency a: and transmits it to the land .line L1.

The system above described is so ar 'anged that any interference between stations is avoided, this result being accomplished, however, by Yhe en'iployment of somewhat complex equipment and tne use of a number of different wave lengths. lt will be understood7 of course, thatl the ship stations shown approach land the ship which is landing may be dropped out of t-he chain of radio repeaters and a new ship starting out from the distant shore may take its place. lVhenever this occurs the frequencies will be readjusted at the various repeater stations so that the translation in frequency occurs in the same order at the diilerent repeater stations. In order to maintain suit-able energy levels for goed transmission it will be possible to have the operators of the various ships whose radio stations are to function as repeater stations adjust the energy transmitted with reference to their geographical location or with reference to the positions of the repeater stations on ships either side of them with which they are to work. The energy level adjustments may be nia-dc by the use of potentiometers in connection with 'the amplifiers or by any other means well known in the prior art. there a regular lane for shiiiping` exists it will readily be posz-iible to arrange a simple and easily followed routine for adjusting the transmission level and ware lengths eniployed at any repeating station so that a minimum of attention by the ships operator will be required to insure satisfactory transmission. i

A secoiuil method is illustrated in Fig. 2. ln accordance with thisI method separate stations are used for traliic in each directionn each. station being arranged to receive on a wave length It] and transmit on a. wave al, or vice versa, depending upon its irl-osition in the chain of repeaters.Y As a result the ware len lihs used from one land statiini to, the other are alternately ai and A? in either direction and no station receives and tra .smits simult-aneonslv on the same ware. length. even though but two wave lengths are employed throughout. "he nature of the apparatus employed will be obvious from the description et Fig. l and the coordination of the apparatus will be clear from a statement of the opeation. Signals incoming from the land line at land station )l will modulate a radio frequency al, which is transn'iitted to ship station No. 2, where is is detected and the detected signal used to .niodulate the radio frequency it, rlhe modulated frequency a2 in turn is radiated to ship station No. et, where it is detected and the detected signal used to modulate a radio frequency al. The radio frequency A, in turn is radiated to the land station Y where it is detected and transmitted to the land line. 'lransn'iission in the opposite direction from the land line at station Y takes place at a radio frequency a2 between the land station and ship station No.

Between ship station No. 3 and ship station No. l transn'iission takes place at frequency )t1 and linally transmission between ship station No. l and land station X taires place at radio frequency A2, the modulated radio frequency being detected at station X and the detected signals transmitted to the land line thereat.

While this arrangement has the advantage of employing only two carrier fre uencies, a certain amount of interference etween tra'lic in the two directions may result in the form of an echo or side tone unless the stations carrying traffic in one direction follow paths well separated from those carrying traiiic in the other direction. For example, should ship station No. l and ship stat-ion No. 3 approach too close together an echo path may be traced from land station X to ship station No. 2 at carrier frequency a, and from ship station No. 2 to ship station llo. 3 at carrier frequency )t2 and then from the latter station back to land station X through ship station No. l. This is a matter which may be readily overcome, however, by keeping the lanes of the ships traveling in the two directions well apart from cach other. Adjustments of the transmission level and the wave lengths employed may be made as described in connection with Fig. l.

A third method of transmitting with the aid of radio repeating stations of the mobile type is illustrated in Fig. 3, where each repeating station receives one wave length al and transmits with wave length a2 or vice versa.. For example, transmission takes place from land station X to ship station No. l at frequency At ship station No. l this frequency is received by the antenna ARL and is then detected and the detected frequency used. to modulate a frequency a2, which radiated. from the antenna ATZ. This frequency is transmitted to ship station No. 2, where it is received by the receiving antenna AR3 and detected. The detected signal is then used to modulate the carrier frequency al, which is radiated from the antenna ATI., to the receiving antenna ATY For transmission in the opposite direction a frequency )t2 is employed in transmitting from land station Y to ship station No. 2, the latter frequency being received by receiving antenna AR3 at the latter po-int. This is translated to a frequency al for radiation from antenna ATB to receiving antenna AR2 of ship station No. l where the frequency is again translated to A, for transmission from antenna AT2 to the receiving antenna AR1 of land station X. This arrangement has the advantage of great simplilication of the apparatus involved in addition to the use of only two frequencies, hut, here again, side tone may result in certain cases. For example, if ship stations No. l and No. 2 approach each other too closely a side tone path may be traced from antenna AT2 at ship station No. l to antenna AR3 at ship station No. 2 at a frequency of A2, being translated at the latter station to a frequency of al, which is transmitted back from antenna AT.s to receiving antenna AR2 at ship station No. 1. This ditliculty may, of course, be avoided by tal;- ing care that the stations are properly separated.

there it is found practicable to balance the transmitter against the receiver, transmission may take place from land station to land station through the intermediate repeater stations without translation in wave length, one wave length being employed for transmission in one direction throughout and one wave length being employed for transmission in the other direction throughout. Figure 4t illustrates a system of this type. Tn this system a single antenna may be used both for 'transmitting and receiving at the repeater station. For example, a ship station No. l a single antenna A2 is shown, the antenna being coupled to a receiving channel RL, through a hybrid coil arrangement l0. An outgoing channel TL2 is connected to the midpoint of the hybrid coil and the two channels are rendered conjugate by balancing the antenna A2 by means of a suitable network N2, in a manner well known in the art. The two channels are interconnected by selective paths, each including high frequency amplifying apparatus with suitable filters on either side of the amplifiers for rendering the paths selective to frequencies al and respectively. Ship station No. 2 may be in all respects identical with that described in connection with ship station No. 1.

The operation is as follows: Signals from the land line at land station X modulate a carrier frequency al which is radiated from the antenna AT1 and received by the antenna AT2 (which may be arranged so as to be selective at either of two frequencies or else made aperiodic so as not to `discriminate between the frequencies) ,and then transmitted to the receiving channel RLT From this channel it will be selected into the upper path by means of the filter selective to frequency al, the modulated carrier being amplified and transmitted through the transmitting path TL2 to the antenna A. The modulated ampliied frequency A1 will then be radiated and transmitted to station No. 2, where a similar operation will take place, the amplified radio frequency al being then radiated to station Y and received by antenna ARAP Transn'iission in the opposite direction will take place at frequency a2. This frequency is received by the antenna its, of station No. 2 and passed into the receiving channel where it is selected by the lilters of the lower path for amplification and transmission to the receiving channel. .From the receiving channel the frequency as is transmitted baclr to the antenna A, for radiation to ship station No. l, where a similar operation takes place. The amplilied frequency A2 is finally radiated from antenna A2 to the receiving antenna. AR, of land station X. The arrangement described in connection with Fig. 4 will be free from any echo or side tone effect, due to proximity of repeater stations, although it requires a very high degree of balance to prevent singor side tone in the individual circuits of each repeater station.

Fig. 5 illustrates a system of a similar type in which reception and transmission take place in both directions at all stations at the same wave length. At land station X. the transmitting and receiving antennae AT, and Al1 of the preceding figures are replaced by a single antenna A, which is coupled to the local receiving and transmitting channel by means of a hybrid coil 11 and balancing network 12 in a manner well understood in the art. The apparatus at the ship stations No. l and No. 2 will be similar to that illustrated in Fig. 4, except that the receiving and transmitting channels associated with the common antenna.l at each ship station will be interconnected by single path containing an amplifier and suitable selective apparatus.

The operation is as follows: Signals incoming from land line Ll niiodulate the radio frequency and after amplification and selection the modulated frequency is 'adiated from the antenna A, to the anten a Aq, of ship station No. 1. The modulated frequency is then passed into the receivinp; channel HL2, amplifiedv by the amplii'ier in the common path and then passed into the transmitting channel TL2 for radiation from the antenna. A,2 to ship station No. 2. At this station a similar operation takes place and the same wave length is finally radiated to the receiving antenna A. atland station Y. Transmission in the opposite direct-ion will obviously take place in a similar manner. This arrangement is subject to the disadvantage that it will require a very perfeet degreeof balance to prevent echoes or howling between adjacent stations. It is ideal, however, in that it employs only one wave length and, aside from. the balancing apparatus, a very simple and inexpensive amplifying arrangement.

Many other combinations of frequencies in repeating stations might be devised but the systems above described may be considered illustrative. It is not, however, intended to limit this system employing mobile or ambulatory repeating devices to any particular system of wave length distribution among the various stations. In this connection, it is pointed out that the use of a frequency control system similar to that disclosed in United States patent to O. B. Blackwell, Serial No. 1,403,835, of January 1T, 1022. or United States patent to J. R. Carson, Serial No. 1,403,841, of January 17, .1922, may be used in connection with the repeater arrangements of the present invention, Fig. 6 illustrates a circuit arrangement embodying this feature. At the land station X, which may be treated as a master station inr accordance with the scheme disclosed in the Carson and Blackwell patents, above referred to, two oscillators Ol and Ol are provided, one of which may generate a frequency of 500,000 cycles, for example, and

he other a frequency of 550,000 cycles, for example. These two frequencies are i1n pressed upon a modulator Ml, thereby producing in the output circuit components having frequencies of 450,000, 500,000` and 550,- 000 cycles. A certain amount of energy from the oscillator Ol is led to the speech moeulator M1, which is also associated with the land line L11, so that the frequency 500,000 cycles may be modulated in accordance with the signals incoming from said line and after being amplified by the amplifier TA1 may be in'ipressed upon the transn'iitting antenna r T1. Obviously, there would be radiated from the antenna AT1 an unmoduleated component of 500,000 cycles, components corren spending to 500,000 cycles i s, the signaling frequency, and frequencies of 450,000 and 550.000" cycles.

t sliip station No. l, these frequencies n'iay be received by the antenna ART An amplifier Er l is associated with the antenna for amplifyii-ig the frequencies and on the output sido of the amplifier three 1u-anches are arranged including filters F2, ll2 and "L respectively. Filter .lf3 passes a band c, :pond-ing J601500000 eye-les s. Filter Fg passes 550,000 cycles and filter F, 450,- 000 cycles. Ai modulator M2 is provided and so associated'A with the branches including ilters l?2 and F"2 that the band of frequencies corresponding to 500,000 cycles i lllil 1 Sie iii) s will beat with the frequency of 550,000 cycles to produce a lower band'corresponding to 50,000 cycles i 8 in the ouput side ot the modulator. This band may be selected and detected by the detecting arrangement DEZ, thereby producing` the signal s in its output. A speech modulator M2 is provided, the signal s being impressed upon said modulator together with the fre quency 550,000 cycles so that the latter free quency will be modulated in accordance With the signal and a band corresponding to 550,- 000 cycles j; s Will appear upon the output side of the modulator. An amplifier EA2 may be provided for impressing the energy upon the traiisinitting antei'ma ATZ. rlChe band corresponding to 550,000 cycles i: s is impressed upon this modulator and the unmodulated frequency of 450,000 cycles is also impressed upon this modulator so that these frequencies are radiated from the antenna AT, in amplified form.

At ship station No. 3 a somewhat similar arrangement is provided. Here the received frequencies are amplified by the amplifier FAT rlhe modulated band o'i 550,000 cycles `i 8 is Selected by a filter FS, While the unn'iodulated frequency ot 50.000 cycles is selected by a filter Fi, and impressed upon the same modulator. As a result, a lower side band corresponding to 100,000 cycles :l: s is produced in the output or' modulator h 3. lrom this band the signal s is selected and detected by the detector DE, so that the signal s is produced upon the output side ot the detector. A speech modulator M3 is provided upon which the signal s is impressed, together ivith the unmodulated freiniency of 450,000 cycles from the filter F3. As a result, the signal is modulated upon a carrier frequency of 450,000 cycles and imprewed upon the amplifier EA,... At the saine time, the unmodulated component of ,i00,000 cycles is selected from the output ot modulator MQ, by the filter F, and impressed upon a harmonic producer l-l. The harmonic producer H may be ot any type well known in the art such, for example, as n. distorting tube. By the action ot this harmonic producer, harmonics ot 100,000 cycles are produced, of which the harmonic corresponding to 500,000 cycles is selected by the filter F", and impressed upon the amplifier EAIV Consequently, the transmitting antenna radiates an unmodulated frequency oi? 500,000 cycles and a .signaling band coniprising 450,000 cycles j: s.

'ihe above illustrations are sufficient to indicate the manner in which the frequency may be transmitted from station to station by successive changes in frequency, all ot the 'frequencies being controlled from a master station X. 'lhe transmission in the opposite direction may take place in a similar manner and it has not been considered necassary, therefore, to illustrate the details of the repeaters at ship .station No. l and ship station No. 4i. lt Will be understood, of course, that the distant land station (not shown) Will act as a master staten for 'transmission inthe opposite direction. It may be considered, for example, as transmitting Athree frequencies f1, ffl-fo and ffl-fo. One -o'i` these three frequencies is modulated and at the first repeater point the signal is detected and by re-modulation and re-amplification, retransmitted on another of the three frequencies. Each time the signal is trans mitted to a repeater staten it Will be detected and modulated upon a different carrier in a manner similar to that described in connec tion With ship stations No. l and No.

t Will be obvious that the general principles herein disclosed may be embodied in many other organizations Widely different from those illustrated Without departing from the lspirit of the invention as deiined in the following claims.

lVhat is claimed is:

l. A radio repeating system comprising terminal receiving and transmitting stations and a plurality of intermediate stations' shitting in position with respect to the terminal stations along routes of travel be tween said terminal stations, means at each intermediate station for receiving and amplifying signals transmitted from the nearest adjacent station on one side and means responsive to the received signals for transmitting the amplified signals to the nearest station on the other side.

2. A radio repeating .system comprising terminal receiving and transmitting stations and a plurality of intermediate stations shifting in position With respect to each other along routes of travel between said terminal stations, means at each 'intermediate station for receiving and amplifying sgnals transmitted from the nearest adjacent station on one side and means responn sive to the received signals for transmitting the amplified signals to the nearest station on the other side.

I5. A radio repeating system comprising terminal stations, each arranged for transmission and reception, and a plurality of intermediate repeating stations arranged to move in a continuous chain from one terminal station to the other, each intermediate station comprising means for receiving` and amplifying signals transmitted from the nearest adjacent station on one side and means responsive to the received signals for transniitting the amplified signals to the nearest adjacent station on the other side.

4L. A radio repeating station comprising` terminal stations, each including means for transmitting and receiving signals, a plurality of movable repeating stations intermediate between the terminal stations, said lin El fl repeating stations moving in an Iendless chain in the spa-ce between the terminal stations so tlfiat a lgiven number of the stations will always be moving between the terminal stations in one direction While other repeating stations Will `be moving` between the terminal stations in the opposite direction, mea-ns at each repeating station for receivn ing and 4amplifying signals transmit-ted trom the nearest station on one side moving in the saine direction and means responsive to the received signals `tor transmitting the :nnpliiied signals to the nearest station on the other side movi-ng in the same direction,

A radio repeating system coin1z rising terminal stations, each arranged to transmit and receive signals at different requen-cies, a plurality oit intermediate repeating stations movable with respect to said terminal stations along routes 'et travel between said terminal stations, means at each repeating station to receive signals transniiit'ted from the nearest adjacent station on one side,

means responsive to the received signals to 'translate the .signals in frequency and means to transmit the signals thus transl-ated in :trequency vto the nearest adjacent station on the other side.

(S, A radio repeating system comprising terminal stati-ons, each arranged to transmit and receive signals at diiilerent frequencies, a plurality ot iiite-rmediate repeating sta,- tiions movable with respect to each other along routes of travel between said terminal stations, means at each repeating .station to receive signa-ls transmit-ted from the nearest adjacent station on one side, means responsive to the received signals to translate the signals vin lfrequency and moans to transmit the signals thus translated in frequency to the nearest adjacent station on the other side.

In testimony whereof, l have signed my name to this specification lthis 7th day ot August, 1923.

iOBERT W. MORRIS. 

